Cardiac arrhythmias, such as ventricular fibrillation and ventricular tachycardia, are electrical malfunctions of the heart, in which regular electrical impulses in the heart are replaced by irregular, rapid impulses. These irregular, rapid impulses can cause the heart to stop normal contractions, thereby interrupting blood flow therethrough. Such an interruption in blood flow can cause organ damage or even death.
Normal heart contractions, and thus normal blood flow, can be restored to a patient through application of electric shock. This procedure, which is called defibrillation, has proven highly effective at treating patients with cardiac arrhythmias, provided that it is administered within minutes of the arrhythmia. In the past, this was not always possible, since defibrillation units were large, and thus not easy to move, and could only be operated by an experienced clinician.
In response to the foregoing drawbacks of defibrillation units, implantable defibrillators were developed. Such defibrillators, however, also have several drawbacks. Specifically, use of a such a defibrillator requires surgery, thereby making their use inconvenient and even undesirable under certain circumstances. Moreover, implantable defibrillators are also costly, both in terms of the device itself and in terms of the cost of the surgery and subsequent treatments.
To address the foregoing drawbacks of implantable defibrillators, portable automatic external defibrillators (hereinafter “AEDs”) were developed. These defibrillators are typically used by trained emergency medical system personnel. The major shortcoming of these defibrillators is the delay between the onset of ventricular fibrillation and the administering of a first shock. It has been estimated that survival decreases by 10% for each minute that passes after the first minute of ventricular fibrillation.
Temporary high risk patients who do not reach an ICD have little protection against sudden cardiac arrest (“SDA”), particularly with the discovery that anti-arrhythmia drugs have been proven to be less effective than a placebo. Accordingly, there exists a need for a defibrillator, preferably a portable, wearable defibrillator, which addresses the foregoing drawbacks of conventional defibrillators.